A simple trick — using one eye to peer through a small hole — may trick the brain into seeing depth in a flat picture

By Stephen Ornes, 19:03 PM November 5, 2013

Want to see a 3-D movie without paying steep ticket prices? Try closing one eye. Then use the other to watch the film through a tiny hole.

In a new study, people reported that a flat scene appeared three-dimensional, or 3-D, when viewed through a small hole with one eye. Some scientists are skeptical about the finding and demand stronger evidence that the approach works.

Modern 3-D technologies use an approach that has been around for almost 200 years. They show a different image to each eye. (...